SC amplifier arrangements (SC is short for switched capacitor) comprise an SC amplifier having an input capacitor that is connected to an input of the SC amplifier arrangement by a clock-controlled switch. A mean input current, and hence an input impedance, of such an SC amplifier arrangement depends on a capacitance of the input capacitor.
SC amplifier arrangements can be used in instrumentation circuits for measuring electrical voltages. In this application, the voltage to be measured is applied to the input of the SC amplifier arrangement. The input current of the SC amplifier arrangement can here cause a change or error in the voltage to be measured, and hence a measurement error. This effect is more pronounced the higher the output impedance of a signal source supplying the voltage to be measured and the higher the input current of the SC amplifier arrangement.